Solar regulators or charger controllers are a crucial part of every solar power system.

Solar regulators allow you to safely control your panels.

They not only switch off the panel when the battery is full, they stop the battery over charging and over discharging; this considerably extends the life of your battery.

You can safely leave the solar panel connected to the battery when you are not there to disconnect it, safe in the knowledge that the battery will not cook and should a problem arise the unit will switch off the charge.

The solar charging controller is connected between a solar cell 12V to 22V and a 12V battery to prevent overcharging. The regulator monitors the battery voltage and switches on the charge when needed, thus keeping your battery in a fully charged state, but not overcharged.

A typical basic charge controller:

This is the one I use for my 60w watt system.

Charge controllers are measured and sold by their A amp rating. The one displayed has a max 5a rating, which at 12v would allow for use of panels up to 60 watts. In reality, most panels output between 13 and 20 volts, so you would probably only ever put through about 3-4a of power. ACCU stands for accumulator which just means battery.

The controller below allows up to 24 amps and also has a handy aux output to gain power from the system while it is running during the day.

It is worth buying a fairly good quality charge controller and think in advance, before you buy, how many watts of panel you intend to use or grow your system to. It will only be a source of frustration if you have bought a 5a controller for the 60w of panel you had at the time, but then are unable to expand the system further unless you buy a higher rated controller first.

Image above is of a 60a controller, which would allow up to about 1.5 kw on a 24v system or 750w at 12v.